Whether you call it Weaver™ style, cross slot, Picatinny, 1913 mil-std or scope rail, often there’s some confusion about these scope mounting systems. Are they the same? Are they similar? Will my Picatinny rings fit a Weaver style base? That’s easy…in the order asked above, no, yes and definitely maybe.

Are they the same? No. The two scope mounting systems were standardized at different times, and I suspect the Weaver style strongly if not almost entirely influenced the Picatinny design.

Are they similar? Yes. When looking at each base head on, they are almost identical, and for scope mounting purposes, those dimensions are interchangeable. When viewing the base from the side, that’s where the critical difference comes to light.

The main difference? The cross slots on the base that the recoil lug or bolt on the rings fit into are wider on the Picatanny system than on the Weaver style system. Also, Picatinny specifications call for even spacing of the cross slots, where the Weaver style system does not have that specification and a few slots are often placed where it best suits mounting a scope.

Will my Picatinny rings fit a Weaver style base? Maybe. If the recoil lug in the rings is small enough, they may work with a Weaver style base, but most often they will not. Yet Weaver style rings will almost always fit Picatinny bases.

If you’re curious enough and want to know, the dimensions for both styles of bases can be found online and remember, that if you’re using Picatinny rings, it will be best to find a Picatinny base as well.
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